Cyclonic vacuum cleaner

ABSTRACT

A cyclone separator having an improved efficiency to remove a broader spectrum of contained particles is disclosed. The cyclone separator is provided with a member positioned to interact with at least the inner portion of a fluid circulating within the cyclone cavity to impart changes in the acceleration of the fluid as it rotates within the cyclone cavity.

This application is a continuation application of U.S. application Ser.No. 09/136,364 filed on Aug. 19, 1998 now U.S. Pat. No. 6,312,594B1.

FIELD OF THE INVENTION

This invention relates to an improved apparatus for separating acomponent from a fluid stream. In one embodiment, the fluid may be a gashaving solid and/or liquid particles and or a second gas suspended,mixed, or entrained therein and the separator is used to separate theparticles and/or the second gas from the gas stream. In an alternateembodiment, the fluid may be a liquid which has solid particles, and/ora second liquid and/or a gas suspended, mixed, or entrained therein andthe separator is used to remove the solid particles and/or the secondliquid and/or the gas from the liquid stream. The improved separator maybe used in various applications including vacuum cleaners, liquid/liquidseparation, smoke stack scrubbers, pollution control devices, mistseparators, an air inlet for a turbo machinery and as pre-treatmentequipment in advance of a pump for a fluid (either a liquid, a gas or amixture thereof) and other applications where it may be desirable toremove particulate or other material separable from a fluid in a cycloneseparator.

BACKGROUND OF THE INVENTION

Cyclone separators are devices that utilize centrifugal forces and lowpressure caused by spinning motion to separate materials of differingdensity, size and shape. FIG. 1 illustrates the operating principles ina typical cyclone separator (designated by reference numeral 10 inFIG. 1) which is in current use. The following is a description of theoperating principles of cyclone separator 10 in terms of its applicationto removing entrained particles from a gas stream, such as may be usedin a vacuum cleaner.

Cyclone separator 10 has an inlet pipe 12 and a main body comprisingupper cylindrical portion 14 and lower frusto-conical portion 16. Theparticle laden gas stream is injected through inlet pipe 12 which ispositioned tangentially to upper cylindrical portion 14. The shape ofupper cylindrical portion 14 and frusto-conical portion 16 induces thegas stream to spin creating a vortex. Larger or more dense particles areforced outwards to the walls of cyclone separator 10 where the drag ofthe spinning air as well as the force of gravity causes them to falldown the walls into an outlet or collector 18. The lighter or less denseparticles, as well as the gas medium itself, reverses course atapproximately collector G and pass outwardly through the low pressurecentre of separator 10 and exit separator 10 via gas outlet 20 which ispositioned in the upper portion of upper cylindrical portion 14.

The separation process in cyclones generally requires a steady flow freeof fluctuations or short term variations in the flow rate. The inlet andoutlets of cyclone separators are typically operated open to theatmosphere so that there is no pressure difference between the two. Ifone of the outlets must be operated at a back pressure, both outletswould typically be kept at the same pressure.

When a cyclone separator is designed, the principal factors which aretypically considered are the efficiency of the cyclone separator inremoving particles of different diameters and the pressure dropassociated with the cyclone operation. The principle geometric factorswhich are used in designing a cyclone separator are the inlet height(A); the inlet width (B); the gas outlet diameter (C); the outlet ductlength (D); the cone height (Lc); the dirt outlet diameter (G); and, thecylinder height (L)

The value d₅₀ represents the smallest diameter particle of which 50percent is removed by the cyclone. Current cyclones have a limitationthat the geometry controls the particle removal efficiency for a givenparticle diameter. The dimensions which may be varied to alter the d50value are features (A)-(D), (G), (L) and (Lc) which are listed above.

Typically, there are four ways to increase the small particle removalefficiency of a cyclone. These are (1) reducing the cyclone diameter;(2) reducing the outlet diameter; (3) reducing the cone angle; and (4)increasing the body length. If it is acceptable to increase the pressuredrop, then an increase in the pressure drop will (1) increase theparticle capture efficiency; (2) increase the capacity and (3) decreasethe underflow to throughput ratio.

In terms of importance, it appears that the most important parameter isthe cyclone diameter. A smaller cyclone diameter implies a smaller d₅₀value by virtue of the higher cyclone speeds and the higher centrifugalforces which may be achieved. For two cyclones of the same diameter, thenext most important design parameter appears to be L/d, namely thelength of the cylindrical section 14 divided by the diameter of thecyclone and Lc/d, the length of the conical section 16 divided by thewidth of the cone. Varying L/d and Lc/d will affect the d₅₀ performanceof the separation process in the cyclone.

Typically, the particles which are suspended or entrained in a gasstream are not homogeneous in their particle size distribution. The factthat particle sizes take on a spectrum of values often necessitates thata plurality of cyclonic separators be used in series. For example, thefirst cyclonic separator in a series may have a large d₅₀ specificationfollowed by one with a smaller d₅₀ specification. The prior art does notdisclose any method by which a single cyclone may be tuned over therange of possible d₅₀ values.

An example of the current limitation in cyclonic separator design isthat which has been recently applied to vacuum cleaner designs. In U.S.Pat. Nos. 4,373,228; 4,571,772; 4,573,236; 4,593,429; 4,643,748;4,826,515; 4,853,008; 4,853,011; 5,062,870; 5,078,761; 5,090,976;5,145,499; 5,160,356; 5,255,411; 5,358,290; 5,558,697; and RE 32,257, anovel approach to vacuum cleaner design is taught in which sequentialcyclones are utilized as the filtration medium for a vacuum cleaner.Pursuant to the teaching of these patents, the first sequential cycloneis designed to be of a lower efficiency to remove only the largerparticles which are entrained in an air stream. The smaller particlesremain entrained in the gas stream and are transported to the secondsequential cyclone which is frusto-conical in shape. The secondsequential cyclone is designed to remove the smaller particles which areentrained in the air stream. If larger particles are carried over intothe second cyclone separator, then they will typically not be removed bythe second cyclone separator but exit the frusto-conical cyclone withthe gas stream.

Accordingly, the use of a plurality of cyclone separators in a series isdocumented in the art. It is also known how to design a series ofseparators to remove entrained or suspended material from a fluidstream. Such an approach has two problems. First, it requires aplurality of separators. This requires additional space to house all ofthe separators and, secondly additional material costs in producing eachof the separators. The second problem is that if any of the largermaterial is not removed prior to the fluid stream entering the nextcyclone separator, the subsequent cyclone separator typically will allowsuch material to pass therethrough as it is only designed to removesmaller particles from the fluid stream.

SUMMARY OF THE PRESENT INVENTION

In accordance with one embodiment of the instant invention, there isprovided an insert for a cyclone separator for separating a materialfrom a fluid, the separator having a longitudinally extending body and awall, the wall having an inner surface and defining an internal cavityhaving an outer portion in which the fluid rotates when the separator isin use and an inner portion, the insert comprising a distinct memberpositioned within the longitudinally extending body to impinge upon atleast a portion of the fluid as it rotates within the cavity and changethe velocity of that portion of the fluid and cause some of the materialto be separated from the fluid while permitting the fluid to maintainsufficient momentum to continue its rotational motion within the body.

In accordance with another embodiment of the instant invention, there isprovided an insert for a cyclone separator for separating a materialfrom a fluid, the separator having a longitudinally extending body and awall, the wall having an inner surface and defining an internal cavityin which the fluid rotates when the separator is in use, the insertcomprising a member having an outer wall spaced from the inner surfaceand configured to impart changes in the rate of acceleration to at leasta portion of the fluid as it rotates within the cavity causing some ofthe material to be separated from the fluid.

In accordance with another embodiment of the instant invention, there isprovided an insert for a cyclone separator for separating a materialfrom a fluid, the separator having a longitudinally extending bodydefining a longitudinal axis and a wall, the wall having an innersurface which defines an internal cavity having an outer portion inwhich the fluid rotates when the separator is in use and an innerportion, the insert comprising a member positioned in the inner portionand having an outer wall which is positioned to interact with at least aportion of the fluid as it rotates in the outer portion of the cavity toimpart to the portion of the fluid different fluid flow characteristicscompared to those of the fluid rotating in the outer portion of thecavity which promote the separation of the material from the fluid.

In one embodiment, the insert may be centrally positioned within thecavity and extend outwardly to impinge upon the portion of the fluid.

In another embodiment, the outer wall is configured to continuouslyimpart changes in the rate of acceleration to the portion of the fluidas it rotates within the cavity.

In another embodiment, the outer wall of the insert interacts with theportion of the fluid to impart to the portion of the fluid a differentspeed, a different direction of travel or a different velocity comparedto that of the fluid rotating in the outer portion of the cavity.

In another embodiment, the outer wall of the insert is configured tocreate an area in the cavity wherein the fluid is travelling at avelocity insufficient to re-entrain all of the separated material. Thearea may extend longitudinally. Further, the area may have a receivingportion for receiving the material which is separated from the fluid.Alternately, the area may extend longitudinally for a finite length andthe insert may be configured to create a plurality of areas at spacedintervals along at least a portion of the length of the insert. If theseparator is vertically disposed, the receiving portion is may bepositioned towards the lower end of the separator and comprises acollecting chamber in which the separated material is collected. If theseparator is vertically disposed, the receiving portion may bepositioned towards the lower end of the separator and be in flowcommunication with a chamber downstream thereof.

In another embodiment, the rotation of the fluid in the outer portiondefines an outer cyclone and the outer wall of the insert is configuredto interact with the portion of the fluid to cause the portion to rotateto define a second cyclone between the outer wall of the insert and theouter cyclone. The outer wall of the insert may have at least one recessprovided therein.

In another embodiment, the outer wall of the insert is positioned andconfigured to direct the portion of the fluid into the inner portion ofthe cavity.

In another embodiment, the outer wall of the insert is configured tointeract with the portion of the fluid to create a dead air spacebetween the outer wall of the insert and the outer portion of thecavity.

In transverse section, the shape of the insert may be circular, apolygon, a continuous n-differentiable curve wherein n≧2 and the seconddifferential is not zero everywhere swept 360 degrees around thelongitudinal axis, a closed non-circular convex closed path or a helix.

In accordance with another embodiment of the instant invention, there isprovided a cyclone separator for separating a material from a fluidcomprising:

(a) a longitudinally extending body having a wall and defining alongitudinal axis, the wall having an inner surface which defines aninternal cavity having an outer portion in which the fluid rotates whenthe separator is in use and an inner portion; and,

(b) an insert comprising a member having an outer wall spaced from theinner surface and positioned to interact with at least a portion of thefluid as it rotates in the outer portion of the cavity to impart to thatportion of the fluid with which it interacts different fluid flowcharacteristics compared to those of the fluid rotating in the outerportion of the cavity which promote the separation of the material fromthe fluid.

Preferably, the outer wall of the insert is spaced at least 0.1 inchesfrom the inner surface and more preferably, at least 0.125 inches.

In one embodiment, at least a portion of the inner surface and at leasta portion of the outer wall of the insert each have a portion which issimilarly configured.

In another embodiment, at least a portion of the inner surface and atleast a portion of the outer wall of the insert are each in the shape ofa continuous n-differentiable curve wherein n≧2 and the seconddifferential is not zero everywhere swept 360 degrees around thelongitudinal axis.

In another embodiment, the internal cavity has, in transverse section,an inner portion in which the fluid rotates when the separator is in useand at least one outer portion positioned external to the inner portionand contiguous therewith, the outer portion of the cavity extendingoutwardly from the inner portion of the cavity and defining a zone inwhich at least a portion of the fluid expands outwardly as it rotates inthe plane defined by the transverse section, the portion of the fluid inthe outer portion of the cavity having different fluid flowcharacteristics compared to those of the fluid rotating in the innerportion of the cavity which promote the separation of the material fromthe fluid.

In another embodiment, in transverse section, the wall extends in acontinuous closed path and has a non-baffled inner surface which definesan internal cavity, the internal cavity having an inner portion in whichthe fluid rotates when the separator is in use, and at least one outerportion positioned external to the inner portion and contiguoustherewith defining a zone in which the wall is configured to impart toat least a portion of the fluid as it rotates in the plane defined bythe transverse section different fluid flow characteristics compared tothose of the fluid rotating in the inner portion of the cavity whichpromote the separation of the material from the fluid.

In another embodiment, the inner surface of the wall is defined by, intransverse section, a continuous non-circular convex closed path, thecavity having an inner portion positioned within the non-circular convexclosed path and at least one outer portion between the inner portion andthe non-circular convex closed path.

The separator may be a dirt filter for a vacuum cleaner, an air inletfor turbo machinery, treatment apparatus positioned upstream of a fluidpump, treatment apparatus positioned upstream of a pump for a gas,treatment apparatus positioned upstream of a pump for a liquid or thelike.

By designing a cyclone separator according to the instant invention, theparameters L/d and Lc/d may vary continuously and differentiably alongthe length of the cyclone axis. Thus, a cyclone may be designed whichwill have a good separation efficiency over a wider range of particlesizes than has heretofore been known. Accordingly, one advantage of thepresent invention is that a smaller number of cyclones may be employedin a particular application than have been used in the past. It will beappreciated by those skilled in the art that where, heretofore, two ormore cyclones might have been required for a particular application,that only one cyclone may be required. Further, whereas in the pastthree to four cyclones may have been required, by using the separator ofthe instant intention, only two cyclones may be required. Thus, in oneembodiment of the instant invention, the cyclone separator may bedesigned for a vacuum cleaner and may in fact comprise only a singlecyclone as opposed to a multi-stage cyclone as is known in the art.

DESCRIPTION OF THE DRAWING FIGURES

These and other advantages of the instant invention will be more fullyand completely understood in accordance with the following descriptionof the preferred embodiments of the invention in which:

FIG. 1 is a cyclone separator as is known in the art;

FIG. 2 is a perspective view of a cyclone separator according to theinstant invention;

FIG. 3 is a cross-section of the cyclone separator of FIG. 2 taken alongthe line 3—3;

FIGS. 4-11 are each alternate embodiments of the cyclone separator ofFIG. 2;

FIGS. 12(a)-(h) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone cavity has a single insertof varying shape;

FIGS. 13(a)-(h) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone cavity has two similarlyshaped inserts of varying shape, one being positioned above the otherand rotated 90°;

FIGS. 14(a)-(h) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone cavity has two similarlyshaped inserts of varying shape, one being positioned above the otherand rotated at other than 90°;

FIGS. 15(a)-(h) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone cavity has two dissimilarlyshaped inserts of varying shape, one being positioned above the other;

FIGS. 16(a)-(h) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone cavity has two dissimilarlyshaped inserts of varying shape, one being positioned above the otherand offset;

FIGS. 17(a)-(f) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone cavity has a single insertof varying shape and wherein the insert has recesses in the outersurface thereof;

FIGS. 18(a)-(f) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone cavity has two similarlyshaped inserts of varying shape, one being positioned above the otherand rotated 90° and wherein the inserts have recesses in the outersurface thereof;

FIGS. 19(a)-(f) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone cavity has a single insertof varying shape and wherein the insert has concave recesses in theouter surface thereof;

FIGS. 20(a)-(f) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone cavity has two similarlyshaped inserts of varying shape, one being positioned above the otherand rotated 90° and wherein the inserts have concave recesses in theouter surface thereof;

FIGS. 21(a)-(f) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone cavity has one or morehelical inserts;

FIGS. 22(a)-(h) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone has a trumpet shape and thecyclone cavity has a single insert of varying shape;

FIGS. 23(a)-(h) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone has a trumpet shape and thecyclone cavity has two similarly shaped inserts of varying shape, onebeing positioned above the other and rotated 90°;

FIGS. 24(a)-(h) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone has a trumpet shape and thecyclone cavity has two similarly shaped inserts of varying shape, onebeing positioned above the other and rotated at other than 90°;

FIGS. 25(a)-(h) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone has a trumpet shape and thecyclone cavity has two dissimilarly shaped inserts of varying shape, onebeing positioned above the other;

FIGS. 26(a)-(h) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone has a trumpet shape and thecyclone cavity has two dissimilarly shaped inserts of varying shape, onebeing positioned above the other and offset;

FIGS. 27(a)-(f) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone has a trumpet shape and thecyclone cavity has a single insert of varying shape and wherein theinsert has recesses in the outer surface thereof;

FIGS. 28(a)-(f) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone has a trumpet shape and thecyclone cavity has a single insert of varying shape and wherein theinsert has recesses in the outer surface thereof which are positionedoff centre;

FIGS. 29(a)-(f) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone has a trumpet shape and thecyclone cavity has two similarly shaped inserts of varying shape, onebeing positioned above the other and rotated 90° and wherein the insertshave recesses in the outer surface thereof;

FIGS. 30(a)-(f) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone has a trumpet shape and thecyclone cavity has a single insert of varying shape and wherein theinsert has concave recesses in the outer surface thereof;

FIGS. 31(a)-(f) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone has a trumpet shape and thecyclone cavity has two similarly shaped inserts of varying shape, onebeing positioned above the other and rotated 90° and wherein the insertshave concave recesses in the outer surface thereof; and,

FIGS. 32(a)-(f) are the perspective view and the respective top planview of further alternate embodiments of the cyclone separator accordingto the instant invention wherein the cyclone cavity has a trumpet shapeand the cyclone cavity has one or more helical inserts.

DESCRIPTION OF PREFERRED EMBODIMENT

As shown in FIGS. 2-10, cyclone separator 30 may comprises alongitudinally extending body having a top end 32, a bottom end 34,fluid inlet port 36, a fluid outlet port 38 and a separated materialoutlet 40.

Cyclone separator 30 has a wall 44 having an inner surface 46 anddefining a cavity 42 therein within which the fluid rotates. Cycloneseparator 30 has a longitudinally extending axis A A which extendscentrally through separator 30. Axis A—A may extend in a straight lineas shown in FIG. 2 or it may be curved or serpentine as shown in FIG.11.

As shown in FIGS. 2, 4, 5, 7, 8, 9 and 10, cyclone separator 30 isvertically disposed with the fluid and material to be separated enteringcyclone separator 30 at a position adjacent top end 32. As shown in FIG.6, cyclone separator 30 is again vertically disposed but invertedcompared to the position show in FIGS. 2, 4, 5, 7, 8, 9 and 10. In thisembodiment, fluid 48 enters cyclone separator 30 at a position adjacentbottom end 34 of the separator. It will be appreciated by those skilledin the art that provided the inlet velocity of fluid 48 is sufficient,axis A—A may be in any particular plane or orientation, such as beinghorizontally disposed or inclined at an angle.

Fluid 48 may comprise any fluid that has material contained therein thatis capable of being removed in a cyclone separator. Fluid 48 may be agas or a liquid. If fluid 48 is a gas, then fluid 48 may have solidparticles and/or liquid particles and/or a second gas contained thereinsuch as by being suspended, mixed or entrained therein. Alternately, iffluid 48 is a liquid, it may have solid particles and/or a second liquidand/or a gas contained therein such as by being suspended, mixed orentrained therein. It will thus be appreciated that the cycloneseparator of the instant invention has numerous applications. Forexample, if fluid 48 is a gas and has solid particles suspended therein,then the cyclone separator may be used as the filter media in a vacuumcleaner. It may also be used as a scrubber for a smoke stack so as toremove suspended particulate matter such as fly ash therefrom. It mayalso be used as pollution control equipment, such as for a car, or toremove particles from an inlet gas stream which is fed to turbomachinery such as a turbine engine.

If fluid 48 is a gas and contains a liquid, then cyclone separator 30may be used as a mist separator.

If fluid 48 is a mixture of two or more liquids, then cyclone separator30 may be used for liquid/liquid separation. If fluid 48 is a liquid andhas a gas contained therein, then cyclone separator 30 may be used forgas/liquid separation. If fluid 48 is a liquid which has solid particlescontained therein, then cyclone separator 30 may be used for drinkingwater or waste water purification.

In the preferred embodiment shown in FIG. 2, wall 44, in transversesection, is in the shape of an ellipse. In the preferred embodimentshown in FIG. 4, wall 44 has a trumpet shape. Such shapes may beprepared by sweeping a continuous n-differentiable curve 360° aroundaxis A—A wherein n is ≧2 and the second derivative is not zeroeverywhere. Preferably, n is ≧2 and ≦1,000, more preferably n≦100 andmost preferably n≦10. If the second derivative is zero at a finitenumber of points, then it may be zero from about 2 to 100 points,preferably from about 2 to about 30 points and, more preferably, at 2 to10 points.

Fluid 48 enters cyclone separator through inlet port 36 and tangentiallyenters cavity 42. Due to the tangential entry of fluid 48 into cavity42, fluid 48 is directed to flow in a cyclonic pattern in cavity 42 inthe direction of arrows 50. Fluid 48 travels in the axial direction incavity 42 from fluid entry port 36 to a position adjacent bottom end 34.At one point, the fluid reverses direction and flows upwardly in thedirection of arrows 52 while material 54 becomes separated from fluid 48and falls downwardly in the direction of arrows 56. Treated fluid 58,which has material 54 separated therefrom, exits cyclone separator 30via outlet port 38 at the top end 32 of cavity 42.

In the alternate embodiment shown in FIGS. 7 and 8, cyclone separator 30may be a unidirectional flow cyclone separator. The cyclone separatoroperates in the same manner as described above with respect to thecyclone separator 30 shown in FIG. 2 except that fluid 48 travelscontinuously longitudinally through cavity 42. Material 54 becomesseparated from fluid 48 and travels downwardly in the direction ofarrows 56. Treated fluid 64, which has material 54 separated therefrom,continues to travel downwardly and exits cyclone separator 30 via outletport 38 at a position below bottom end 34 of cavity 42.

As exemplified in the FIGS. 2-10, cyclone separator may have a varietyof shapes. In particular, cyclone separator may have an outer rotationalwall 44 which is of any shape known in the industry. For example, outerwall 44 may be either cylindrical (see for example FIGS. 12(a)-(h)) orfrusto-conical in shape.

In one preferred embodiment, cavity 42 has an inner portion in whichfluid rotates as it travel longitudinally in cyclone separator 30 and anouter portion exterior thereto but contiguous therewith. The outerportion of cavity 42 may extend outwardly from the inner portion of thecavity to define a zone in which at least a portion of fluid 48 expandsoutwardly as it rotates in a plane defined by the transverse sectionwhereby the portion of the fluid in the outer portion of cavity 42 hasdifferent fluid flow characteristics compared to those of fluid 48rotating in the inner portion of cavity 42 which promote the separationof the material from the fluid. Such a configuration for wall 44 ofcavity 42 is disclosed in co-pending application number 09/136,867entitled CYCLONE SEPARATOR HAVING A VARIABLE TRANSVERSE PROFILE filedconcurrently herewith now U.S. Pat. No. 6,168,716 B1, all of which isincorporated herein by reference.

Alternately, outer wall 44 of cavity 42 may be in the shape of acontinuous n-differentiable curve wherein n is ≧2 and the seconddifferential is not zero everywhere, swept 360° around the longitudinalaxis of cavity 42 (see for example FIGS. 22(a)-(h)). Such aconfiguration of outer wall 44 of cavity 42 is disclosed in co-pendingapplication number 09/136,366 entitled CYCLONE SEPARATOR HAVING AVARIABLE LONGITUDINAL PROFILE filed concurrently herewith now U.S. Pat.No. 6,277,278 B1, all of which is incorporated herein by reference.

As shown in FIGS. 5, 8 and 10, fluid 48 may enter cavity 42 axially. Insuch a case, fluid entry port 36 is provided, for example, at top end 32of cyclone separator 30. A plurality of vanes 60 are provided to causefluid 48 to flow or commence rotation within cavity 42. It would beappreciated by those skilled in the art that fluid 48 may enter cavity48 from any particular angle provided that fluid entry port 36 directsfluid 48 to commence rotating within cavity 42 so as to assist ininitiating or to fully initiate, the cyclonic/swirling motion of fluid48 within cavity 42.

Referring to FIG. 6, cyclone separator 30 is vertically disposed withfluid entry port 36 positioned adjacent bottom end 34. As fluid 48enters cavity 42, it rises upwardly and is subjected to a continuouslyvarying acceleration along inner surface 46 of cavity 42. Gravity willtend to maintain the contained material (if it is heavier) in theacceleration region longer thereby enhancing the collection efficiency.At one point, the air reverses direction and flows downwardly in thedirection of arrow 64 through exit port 38. Particles 54 becomeseparated and fall downwardly to bottom end 34 of cyclone separator 30.If bottom end 34 is a contiguous surface, then the particles willaccumulate in the bottom of cyclone separator 30. Alternately, opening40 may be provided in the bottom surface of cyclone separator 30 so asto permit particles 54 to exit cyclone separator 30.

It will also be appreciated that cyclone separator 30 may have a portionthereof which is designed to accumulate separated material (for example,if the bottom surface of the cyclone separator FIG. 6 were sealed) or,if the bottom of cyclone separator 30 of FIG. 5 had a collection chamber62 (which is shown in dotted outline) extend downwardly from outlet 40.Alternately, outlet 40 may be in fluid communication with a collectionchamber 62. For example, as shown in FIG. 4, collection chamber 62 ispositioned at the bottom of and surrounds outlet 40 so as to be in fluidcommunication with cyclone separator 30. Collection chamber 62 may be ofany particular configuration to store separated material (see FIGS. 7and 8) and/or to provide a passage by which separated material 54 istransported from cyclone separator downstream (see FIG. 4) provided itdoes not interfere with the rotational flow of fluid 48 in cavity 42.

According to the instant invention, an insert 70 is positioned withincavity 42. Insert 70 has an upstream end 72, a downstream end 74 and awall 76 extending between upstream end 72 and downstream end 74. Wall 76has an outer surface 78. In one embodiment, insert 70 may be hollow andhave an inner cavity 80. This particular configuration is advantageousif cyclone separator 30 is a reverse flow separator as shown in FIG. 2whereby fluid 48, after material 54 has been separated therefrom,travels upwardly through cavity 80 of insert 70 to fluid outlet port 38.It will be appreciated that if cyclone separator 30 is a unidirectionalflow separator as shown in FIGS. 7 and 8, that insert 70 may be a closedor a solid member.

Insert 70 is a distinct member positioned within cavity 42 to impingupon at least a portion fluid 48 as it rotates within cavity 42 therebychanging the speed, the direction of travel or the velocity of the fluidand causing some of the material contained in fluid 48 to be separatedfrom fluid 48. It will be appreciated that insert 70 does not impingupon fluid 48 to a degree whereby the cyclonic motion of fluid 48 incavity 42 is prevented. Instead, insert 70 impinges to a sufficientdegree to cause at least some of the contained material to be separatedfrom fluid 48 while still permitting fluid 48 to maintain sufficientmomentum to continue its rotational motion within cavity 42.

When fluid 48 rotates in a cyclonic pattern within cavity 42, it willrotate only in the outer portion of cavity 42. The inner portion ofcavity 42 will comprise a low pressure area where fluid 48 is stagnantor, in the case of a reverse flow cyclone, fluid 48 is travellingupwardly through the dead air space 75 in the centre of cavity 42.Insert 70 may be mounted (e.g. from above or from below cycloneseparator 30) within this inner portion and extend radially outwardlyfrom the inner portion so as to interact with at least a portion offluid 48 as it rotates in the outer portion of cavity 42 to impart tothe portion of the fluid with which it interacts different fluid flowcharacteristics compared to those of fluid 48 rotating in the outerportion of cavity 42 which promote the separation of the material fromthe fluid. For example, insert 70 may interact with fluid 48 to impartto at least a portion of fluid 48 a different speed, a differentdirection of travel or a different velocity compared to that of fluid 48rotating in the outer portion of cavity 42.

Preferably, outer wall 76 of inset 70 is spaced from inner surface 46and is configured to impart changes, and more preferably to impartcontinuous changes, in the rate of acceleration to at least a portion offluid 48 as it rotates within cavity 42 causing some of the material tobe separated from fluid 48.

In order to allow cyclone separator 30 to achieve a good separationefficiency over a wider range of small particle sizes, wall 76 isconfigured to impart changes in one or more of the speed, direction oftravel, velocity and the rate of acceleration of fluid 48 as it rotateswithin cavity 42. By allowing fluid 48 to be subjected to such varyingfluid flow characteristics, different size particles may be separatedfrom fluid 48 at different portions along the path of travel of fluid 48in cavity 42.

In one embodiment, insert 70 may be configured to impart changes to therate of acceleration of fluid 48 as it travels longitudinally throughcavity 42. Alternately, or in addition, insert 70 may be configured toimpart changes in the rate of acceleration of fluid 48 as it travelstransversely around wall 44.

For example, if the rate of acceleration continually increases along thelength of cyclone separator 30, as would be the case of FIG. 4,continuously finer particles would be separated as the fluid proceedsfrom the top end 32 to bottom end 34. A boundary or prendtl layer whichexists along inner surface 46 of wall 44 and outer surface 78 of wall 76provides low flow or low velocity zones within which the separatedmaterial may settle and not become re-entrained by the faster moving airrotating within cavity 42. As fluid 48 travels downwardly through thecyclone separator shown in FIG. 4, the contained material, which forexample may have a higher density then that of the fluid, would besubjected to continuously increasing acceleration and would be separatedfrom the fluid and travel downwardly along inner surface 46 of wall 44and outer surface 78 of wall 76 in the boundary or prendtl layer. As thefluid travels further downwardly through cyclone separator 30, the fluidwould be accelerated still more. Thus, at an intermediate level ofcyclone separator 30 of FIG. 4, fluid 48 would be travelling at an evengreater rate of speed compared to the top end 32 resulting in even finercontained material becoming separated. This effect would continue asfluid 48 rotates around inner surface 46 to bottom end 34.

In another embodiment, the acceleration may continually decreasethroughout the length of cyclone separator 30. In another embodiment,the acceleration may vary between continuously increasing andcontinuously decreasing along the length of cyclone separator 30.

In the preferred embodiment shown in FIG. 2, fluid 48 is subjected tochanges in its rate of acceleration as it travels transversely aroundwall 44. As shown in FIG. 2, cavity 42 and insert 42 are elliptical intransverse section and have a major axis a—a and a minor axis b—b. Theportion of maximum curvature of inner surface 46 and outer surface 78 inthe transverse plane is denoted by C_(max) and the portion of minimumcurvature of inner surface 46 and outer surface 78 in the transverseplane is denoted by C_(min). By allowing fluid 48 to be subjected tovarying acceleration as it rotates in the transverse plane, differentsize particles may be separated from fluid 48 at different portionsalong the circumference of cyclone separator 30. For example, theacceleration of fluid 48 would increase along sector C_(max) of cycloneseparator 30 and particles having a different density would be separatedat this portion of the circumference. Similarly, for example, theacceleration of fluid 48 would decrease along sector C_(min) of cycloneseparator 30 and particles having a different density would be separatedat this portion of the circumference. A boundary or prandtl layer whichexists along inner surface 46 of wall 44 and outer surface 78 of wall 76provides a low flow or a low velocity zone within which the separatedmaterial may settle and not become re-entrained by the faster moving airrotating within cavity 42.

Increasing the diameter of insert 70 decelerates the fluid. Thecontained material, which has a different density to the fluid wouldtherefore change velocity at a different rate then the fluid. Forexample, if the contained material comprised particles which had ahigher density, they would decelerate at a slower rate then fluid 48 andwould therefore become separated from fluid 48. As the space betweeninner surface 46 and outer surface 78 widens, fluid 48 would accelerate.Once again, the denser particles would be slower to change speed andwould be travelling at a slower rate of speed than fluid 48 as fluid 48enters the wider portion of cavity 42 thus again separating the solidparticles from fluid 48. It would be appreciated that if the particleswhere less dense then fluid 48, they would also be separated by thisconfiguration of insert 70.

If fluid 48 comprises a mixture of two fluids which are to be separated,it is particularly advantageous to include in insert 70 at least oneportion which is configured to decrease the rate of acceleration offluid 48 as it passes through that portion of the separator. In thisconfiguration, the less dense fluid would decrease its velocity tofollow the contours of outer surface 78 more rapidly then the denserfluid (which would have a higher density), thus assisting in separatingthe less dense fluid from the more dense fluid.

In one preferred embodiment, at least a portion of inner surface 46 anda portion of outer surface 78 are the same and, more preferably, innersurface 46 and outer surface 78 are of a similar shape, but spacedapart, for the entire length of insert 70 (see FIGS. 2-6). Preferably,any point on outer surface 78 is at least 0.1 inches from inner surface46 and, most preferably, inner surface 46 and outer surface 78 arespaced at least 0.125 inches apart.

Insert 70 may be of several different configurations. As shown in thedrawings. Insert 70 may be in the form, in transverse section, of acontinuous closed convex path such as elliptical (see FIG. 2) orcircular (see FIGS. 12(e) and (f)), a flat rectangular member (see FIGS.12(a)and (b)), a polygon such as a triangle (see FIGS. 12(c) and (d)) asquare (see FIGS. 12(g) and (h)) or a polygon having a larger number ofsides, or a helix (see FIGS. 21(a)-(e)). If insert 70 is a helix, then,as shown in FIG. 9, insert 70 may have a central core 82 which defines alongitudinally extending channel (or cavity 80) within cavity 42.Helical vane 84 is provided on the exterior surface of central core 82.If cyclone separator 30 is a unidirectional flow separator, it will beappreciated that central core 82 need not be hollow. Further, upstreamend 72 of helical vane 84 may be affixed at a position above cavity 42.Similarly, downstream end 74 of helical vane 84 may be secured inposition at a point below cavity 42 thereby not requiring a central core82.

Alternately, insert 70 may be in the shape of a continuousn-differentiable curve swept 360° around axis A—A wherein n is ≧2 andthe second derivative is not zero everywhere. Preferably, n is ≧2 and≦1000, more preferably n is ≦100 and most preferably, n is ≦10. If thesecond derivative is zero at a finite number of points, then it may bezero from about 2 to 100 points, preferably from about 2 to about 30points and, more preferably, at 2 to 10 points. For example, as shown inFIG. 4, the shape of insert 70 is characterized as a trumpet shape.

The exact position and shape of insert 70 will vary depending uponseveral factors including the transverse thickness of the cyclonic flowof fluid 48 which is created in cavity 42 and the shape of wall 44.

It will be appreciated that in one embodiment, insert 70 comprises anouter surface 78 all of which is configured to continuously impartmomentum or directional changes on the fluid as it rotates within cavity42. Alternately, only a portion of outer surface 78 of insert 70 may beso configured. The interaction with fluid 48 may impart changes in thespeed, direction of travel or rate of acceleration of fluid 48 as itrotates in cavity 42 in addition to those imparted by wall 44 thuspromoting the separation of contained material. The interaction may alsospawn one or more second cyclones 77 which separate the containedmaterial in the same manner as the main cyclone and/or one or more deadair spaces 75 (low velocity zones) in which the separated material maytravel to a collecting chamber 62 without undue re-entrainment.

As shown in FIG. 12(a), wall 44 is cylindrical defining a cylindricallyextending cavity 42. A thin longitudinally extending rectangular memberis centrally positioned therein an is co-terminus with top and bottomends 32 and 34 of cavity 42. As shown in top plan view in FIG. 12(b),fluid 48 circulates in the direction shown by arrow 50 in cavity 42 thuscreating a cyclone that travels around inner surface 46 of wall 44. Asreferred to herein, the portion of cavity 42 in which fluid 48 socirculates is referred to as the “outer portion” of cavity 42. Internalof the outer portion of cavity 42 is the inner portion of cavity 42.Insert 70 is positioned within the inner portion of cavity 42 andextends radially outwardly into the outer portion of cavity 42 so as tointeract with at least a portion of fluid 48 as it rotates within cavity42. As the radial inner portion of fluid 48 interacts with outer surface78 of insert 70, a portion of fluid 48 is induced to form a secondcyclone 77 within cavity 42. As shown in FIG. 12(b), two second cyclones77 would be created, each on an opposed surface 78 of insert 70.

In cavity 42, the main cyclone is generally generated by tangentiallyfeeding fluid 48. Second cyclones 77 are preferably generated byconfiguring insert 70 to create a local pressure differential within themain cyclone. Such local pressure differentials may be created byshearing fluid 48 over outer surface 78 of insert 70 or by boundarylayer delimination when the Reynolds number >3,000.

If second cyclone 77 is a rapidly rotating cyclone similar to thecyclone in the outer portion of cavity 42, then second cyclone 77 isdesigned to promote the separation of material contained in fluid 48.Alternately, second cyclone 77 may be a relatively slow moving cyclonewhich is designed to create a fluid stream which entrains the materialwhich is separated from fluid 48 by the cyclone in the outer portion ofcavity 42 and to transport the separated material 54 downstream to aposition external to cavity 42 such as a collecting chamber 62. Further,insert 70 may be configured to spawn one or more second cyclones 77which rotate in the opposite direction to the cyclone in the outerportion of cavity 42. In another embodiment, insert 70 may be configuredto spawn one or more second cyclones 77 which have an axis of rotationdifferent to axis A—A.

Outer surface 78 of wall 76 may be configured to define an area incavity 42 wherein fluid 48 is travelling at a velocity insufficient tore-entrain all of the material which is separated from fluid stream 48.According to this embodiment, when fluid 48 enters such a low pressurezone or a dead air space 75 internal of the cyclone rotating aroundinner surface 46, the rate of travel of fluid 48 would diminishsufficiently so that the material contained in fluid 48, which has adifferent density, would become separated from fluid 48 and may settledownwardly through the dead air space 75 or the low pressure zonewithout re-entrainment, or at least without substantial reentrainment,of material 54 into fluid 48.

As shown in FIGS. 12(c)-12(h), the number of second cyclone 77 whichwill be created will vary depending upon the transverse section ofinsert 70. Second cyclones 77 increase the separation efficiency ofcyclone 30. However, as second cyclone 77 results in a pressure drop incyclone separator 30, the number and size of second cyclone 77 ispreferably selected to produce the desired separation with an acceptablepressure drop. For example, if incoming fluid 48 contains a largeparticle load and/or fine particles to be separated, then it ispreferred to configure insert 70 to spawn one or more second cyclones77. As the particle load increase, or the particle size decreases, thenit is preferred to configure insert 70 to produce an increased number ofsecond cyclones 77. Further, as the size of the particles to beseparated decreases, then it is preferred to configure insert 70 tospawn one or more cyclones having a smaller diameter.

As shown in FIGS. 13(a)-13(h), a plurality of inserts may be provided,one positioned above the other. If two or more inserts are used, each ofwhich has a different configuration, then different second cyclones 77may be created, each of which is designed to remove particles having adifferent size distribution. Thus second cyclones 77 which have adifferent d₅₀ value may be produced. It will be appreciated that ifinsert 70 has a non-symmetrical transverse section, then second cyclones77 having different d₅₀ values may be created by the same insert.Alternately each insert 70 may create one or more second cyclones 77having the same d₅₀ value and different inserts 70 are used to spawnsecond cyclones 77 having a different d₅₀ value.

Preferably, as shown in FIGS. 13(a)-13(h), an upper insert 90 ispositioned immediately above lower insert 92 so as to, in effect, definea continuous insert. Further, a shown in FIGS. 13(a)-13(h), upper insert90 may be rotated at 90° with respect to lower insert 92 and, as shownin FIGS. 14(a)-14(h), upper insert 90 may be rotated at an angle otherthan 90° with respect to lower insert 92. According to this embodiment,each second cyclone 77 would exist for only part of the longitudinallength F of cavity 42. For example, referring to FIGS. 13(a), (b),insert 90 would create second cyclones 77 a having one particular d₅₀value which would extend along length h1 of cyclone separator 30. Lowerinsert 92 would create second cyclones 77(b) having another d₅₀ valuewhich would extend along length h2 of cyclone separator 30.

As shown in FIGS. 15(a)-15(h), upper and lower inserts 90 and 92 may beof different shapes which are centred one above the other. Alternately,as shown in FIG. 16(a)-16(h), upper and lower inserts 90 and 92 may beof different shapes and may be radially offset from each other.

In the preferred embodiment shown in FIGS. 17(a)-17(f), insert 70 isprovided with recesses 94 in outer surface 78 of insert 70. At least onerecess 94 is provided on insert 70 and, preferably, at least one recess94 is provided on each outer surface 78 of insert 70. Recess 94 definesa dead air space (a region of low velocity or low flow) between secondcyclones 77 within which the separated material may travel to bottom end32 without substantial re-entrainment and, preferably, without anysignificant re-entrainment. The creation of dead air spaces 75 arebeneficial if fluid 48 has a large load of contained material which isto be removed by one or more cyclone separators 30.

As discussed above, cyclone separator 30 may be provided with aplurality of inserts 70 each of which has recesses 94 provided insurfaces 78 thereof. These inserts may be rotated at a 90° angle withrespect to each other as shown in FIGS. 18(a)-18(f). Alternately, upperand lower inserts 90 and 92 may be rotated at an angle other than 90°with respect to each other or they may be offset from each other or theymay be of differing shapes.

In the preferred embodiment shown in FIGS. 19(a)-19(f), outer surfaces78 of insert 70 are concave or “bow” shaped and have a plurality ofsections 96 between adjacent “bow” shaped outer surfaces 78. Sections 96interact with a portion of fluid 48 rotating along wall 44 to direct aportion of fluid 48 into the inner portion of cavity 42 thus assistingin the creation of second cyclones 77. Such upper and lower inserts 90and 92 may be of any particular shape as discussed above and may bepositioned with respect to each other in any manner as discussed above.For example, as shown in FIGS. 20(a)-20(f), two inserts 70 havingconcave outer surfaces 78 may be positioned one above the other androtated at a regular angle with respect to each other.

As shown in FIGS. 21(a)-21(b), insert 70 may have a longitudinallyextending central core 82 having a single helical vane 84 positionedthere around causing fluid 48 to travel there along in the direction ofarrow 98. A first or outer cyclone rotates in the outer portion ofcavity 42 around wall 44.

In an alternate embodiment shown in FIGS. 21(c) and (d), insert 70 mayhave two helical vanes 84 which are symmetrically positioned around core82. Alternately, as shown in FIGS. 21(e) and 21(f), each helical vane 84may be discontinued along central portion 100 of core 82 thuseffectively creating an upper set of helical vanes 84 and a lower set ofhelical vanes 84. Helical insert have a wide d₅₀ range compared withother inserts. Therefore, a helical insert is preferred if the containedparticles in fluid 48 have a wide particle size range.

FIGS. 22(a)-22(h) through 32(a)-32(f) show a similar series ofconfigurations to those shown in FIGS. 12(a)-12(h) through 21(a)-21(f).The main difference between the series of drawings is that in the latterseries, cavity 42 is cylindrical in shape as defined by wall 44. In theformer series, outer wall 44 is trumpet shaped such that the diameter ofcavity 42 narrows from upper end 32 to bottom end 34. Accordingly, it ispreferred in such an embodiment that insert 70 narrows from upstream end72 to downstream end 74. A trumpet shaped outer wall 44 produces a maincyclone having a wide d₅₀ range compared with the cyclone created by acylindrical wall 44 and is preferred if the contained particles in fluid48 have a wide particle size range.

In the longitudinal direction defined by axis A—A, inner surface 46 iscontinuous. By this term, it is meant that, while inner surface 46 maychange direction longitudinally, it does so gradually so as not tointerrupt the rotational movement of fluid 48 within cavity 42. It willbe appreciated that, in the longitudinal and/or the transversedirection, that inner surface 46 of cavity 42 and/or outer surface 78 ofwall 76 may be defined by a plurality of straight line portions, each ofwhich extends for a finite length. Inner surface 46 may be defined by 3or more such segments, preferably 5 or more such segments and mostpreferably, 10 or more such segments.

It will also be appreciated that, depending upon the degree of materialwhich is required and the composition of the material in the fluid to betreated that a plurality of cyclone separators each of which, or onlysome. of which, may be connected in series. The plurality of separatorsmay be positioned side by side or nested (one inside the other) as isshown in FIG. 10.

It will also be appreciated that if cyclone separator 30 is a reverseflow cyclone, that insert 70 may be hollow, (see for example FIG. 30(e))so as to provide an internal passage through which fluid 48 may travelafter material 54 has been separated therefrom.

What is claimed is:
 1. A vacuum cleaner comprising: (a) a dirty airinlet in fluid communication with a source of suction, the source ofsuction producing an air stream through the vacuum cleaner; (b) a dirtfilter positioned downstream from the dirty air inlet, the dirt filtercomprising at least first and second cyclone separation stages; (c) thefirst cyclone separation stage comprising an upright cyclone having afirst end, a second end positioned below the first end, a dirty airinlet positioned adjacent the first end, a cyclonic flow region and acyclonic flow region exit; and, (d) the second cyclonic separation stagepositioned downstream from the first cyclone separation stage andcomprising a plurality of inverted cyclones, each inverted cyclonehaving a first wider end, a second narrower end positioned above thefirst wider end, a dirty air inlet positioned adjacent the first widerend, a cyclonic flow region and a cyclonic flow region exit.
 2. Thevacuum cleaner as claimed in claim 1 wherein the plurality of invertedcyclones are positioned side by side.
 3. The vacuum cleaner as claimedin claim 1 further comprising at least one separated dirt storagechamber positioned to receive material separated from the air stream asthe air stream passes through the plurality of inverted cyclones and thecyclonic flow region exit of each inverted cyclone is positioned abovethe separated dirt storage chamber.
 4. The vacuum cleaner as claimed inclaim 1 further comprising at least one separated dirt storage chamberpositioned to receive material separated from the air stream as the airstream passes through the dirt filter and the cyclonic flow region exitof each inverted cyclone is positioned above the separated dirt storagechamber.
 5. The vacuum cleaner as claimed in claim 1 wherein eachinverted cyclone tapers from the first wider end to the second narrowerend.
 6. A vacuum cleaner comprising: (a) a dirty air inlet in fluidcommunication with a source of suction, the source of suction producingan air stream through the vacuum cleaner; (b) a dirt filter positioneddownstream from the dirty air inlet, the dirt filter comprising at leastfirst and second cyclone separation stages; (c) the first cycloneseparation stage comprising at least one cyclone, each cyclone having afirst end, a second end positioned below the first end, a dirty airinlet positioned adjacent the first end, a cyclonic flow region and acyclonic flow region exit; and, (d) the second cyclonic separation stagepositioned downstream from the first cyclone separation stage andcomprising at least one inverted cyclone, each inverted cyclone having afirst wider end, a second narrower end positioned above the first widerend, a dirty air inlet positioned adjacent the first wider end, acyclonic flow region and a cyclonic flow region exit.
 7. The vacuumcleaner as claimed in claim 6 wherein the second cyclonic cleaning stageincludes a plurality of inverted cyclones.
 8. The vacuum cleaner asclaimed in claim 7 wherein the first cyclonic cleaning stage has onecyclone.
 9. The vacuum cleaner as claimed in claim 7 wherein theplurality of inverted cyclones are positioned side by side.
 10. Thevacuum cleaner as claimed in claim 8 further comprising at least oneseparated dirt storage chamber positioned to receive material separatedfrom the air stream as the air stream passes through the dirt filter andthe cyclonic flow region exit of each of the inverted cyclones ispositioned above the separated dirt storage chamber.
 11. A vacuumcleaner comprising: (a) a dirty air inlet in fluid communication with asource of suction, the source of suction producing an air stream throughthe vacuum cleaner; (b) a dirt filter positioned downstream from thedirty air inlet, the dirt filter comprising at least first and secondcyclone separation stages; (c) the first cyclone separation stagecomprising at least one cyclone, each cyclone having a first end, asecond end positioned below the first end, a dirty air inlet positionedadjacent the first end, a cyclonic flow region and a cyclonic flowregion exit; and, (d) the second cyclonic separation stage positioneddownstream from the first cyclone separation stage and comprising atleast one inverted unidirectional cyclone, each inverted unidirectionalcyclone having a first wider end, a second narrower end positioned abovethe first wider end, a dirty air inlet positioned adjacent the firstwider end, a cyclonic flow region and an air exit positioned adjacentthe second end.
 12. The vacuum cleaner as claimed in claim 11 whereinthe second cyclonic cleaning stage includes a plurality of invertedcyclone.
 13. The vacuum cleaner as claimed in claim 12 wherein the firstcyclonic cleaning stage has one cyclone.
 14. The vacuum cleaner asclaimed in claim 13 further comprising at least one separated dirtstorage chamber positioned to receive material separated from the airstream as the air stream passes through the dirt filter and the air exitof each inverted unidirectional cyclone is positioned above theseparated dirt storage chamber.
 15. A vacuum cleaner comprising: (a) adirty air inlet in fluid communication with a source of suction, thesource of suction producing an air stream through the vacuum cleaner;(b) a dirt filter positioned downstream from the dirty air inlet, thedirt filter comprising at least first and second cyclone separationstages; (c) the first cyclone separation stage comprising at least onecyclone, each cyclone having a first end, a second end positioned belowthe first end, a dirty air inlet positioned adjacent the first end, acyclonic flow region and a cyclonic flow region exit; and, (d) thesecond cyclonic separation stage positioned downstream from the firstcyclone separation stage and comprising a plurality of invertedunidirectional cyclones having a first wider end, a second narrower endpositioned above the first wider end, a dirty air inlet positionedadjacent the first wider end, a cyclonic flow region and an air exitpositioned adjacent the second end.
 16. The vacuum cleaner as claimed inclaim 15 further comprising at least one separated dirt storage chamberpositioned to receive material separated from the air stream as the airstream passes through the dirt filter and the air exit of each invertedunidirectional cyclone is positioned above the separated dirt storagechamber.
 17. A vacuum cleaner comprising: (a) a dirty air inlet in fluidcommunication with a source of suction, the source of suction producingan air stream through the vacuum cleaner; (b) a dirt filter positioneddownstream from the dirty air inlet, the dirt filter comprising at leastfirst and second cyclone separation stages; (c) the first cycloneseparation stage comprising at least one cyclone having a first end, asecond end positioned below the first end, a dirty air inlet positionedadjacent the first end, a cyclonic flow region and a cyclonic flowregion exit; (d) the second cyclonic separation stage positioneddownstream from the first cyclone separation stage and comprising atleast one inverted cyclone, each inverted cyclone having a first end, asecond end positioned above the first end, a dirty air inlet positionedadjacent the first end, a cyclonic flow region and a cyclonic flowregion exit; and, (e) at least one separated dirt storage chamberpositioned to receive material separated from the air stream as the airstream passes through the dirt filter and the cyclonic flow region exitof each inverted cyclone is positioned above the separated dirt storagechamber.
 18. The vacuum cleaner as claimed in claim 17 wherein eachinverted cyclone tapers from the first end to the second end wherein thesecond end is narrower than the first end.
 19. The vacuum cleaner asclaimed in claim 17 wherein the second cyclonic cleaning stage includesa plurality of inverted cyclones.
 20. The vacuum cleaner as claimed inclaim 19 wherein the plurality of inverted cyclone separators arepositioned side by side.
 21. The vacuum cleaner as claimed in claim 17wherein the at least one separated dirt storage chamber is positioned ina space contiguous with the cyclonic flow region of the at least oneinverted cyclone.
 22. The vacuum cleaner as claimed in claim 17 whereinthe at least one separated dirt storage chamber is positioned in a spacewhich surrounds a portion of the cyclonic flow region of the at leastone inverted cyclone.
 23. The vacuum cleaner as claimed in claim 17wherein the at least one separated dirt storage chamber is in fluidcommunication with the cyclonic flow region of the at least one invertedcyclone.